Connecting an instrument, home stereo, or microphone to your sound card

You need a cable with the correct plug on the end of it to connect an instrument or mic to your sound card. Low-priced sound cards usually have 1/8 inch analog jacks (inputs) marked Mic and Line, and might have a digital input marked S/PDIF. The Line input is the correct one for most electronic instruments such as electric guitars. The Mic input is calibrated to accept the input from microphones (however, you can usually get a better recorded sound by plugging a mic into a preamp or mixer with preamp, and plugging the preamp or mixer into the Line input). The S/PDIF input is the one to use for digital audio sources such as samplers and some CD players. Guitar cables usually have a 1/4 inch plug on the end, so to connect an electric guitar to a 1/8 inch jack, you need a 1/4 inch-to-1/8 inch adapter, which is readily available at electronics supply stores. If you’re not sure what kind of inputs your sound card has, you can actually measure their width (diameter).

If you have a more professional-grade sound card, the input jacks will probably be 1/4 inch, and you might also have some XLR inputs for low-impedance microphones, and S/PDIF and possibly AES/EBU connections for digital input and output. If your microphone cable has an XLR plug on the end of it (an XLR plug has 3 pins sticking out of it), and your sound card only has 1/4 inch input jacks, you need to put an XLR-to-1/4 inch adapter on the end of your microphone cable.

The following table summarizes the possible sound card inputs, types of cables required, and the inputs to plug into.

Type of sound card inputs	Cables and adapters needed	Inputs to plug into
1/8 inch Mic and Line	For most electric instruments: 1/4 inch balanced cable connected to 1/4 inch-to-1/8 inch adapter. For mics that have an XLR plug on their cable: XLR-to-1/4 inch adapter connected to 1/4 inch-to-1/8 inch adapter.	Plug instruments into the Line input; plug microphones into the Mic input. Alternatively, plug mics into preamps, and plug preamps into Line inputs.
1/4 inch Left and Right	No adapter required for normal electric instrument cable. For mics that have an XLR plug on their cable: XLR-to-1/4 inch adapter.	Plug both instruments and mics into the Left or Right input of a pair of inputs. If your instrument has stereo pickups and a stereo cable, you can plug the cable into both the Left and Right inputs.
1/4 inch Left and Right, XLR Left and Right	No adapters required	Plug instruments into the 1/4 inch Left, Right, or both inputs. Plug a mic into the XLR Left or XLR Right input.
S/PDIF (Sony/Phillips Digital Interface)	No adapters required. Use a a 75 ohm coaxial video cable, or special S/PDIF cable. Do not use standard stereo component cables.	Connect your digital source (probably a sampler or CD player with digital outputs) to your sound card’s S/PDIF input using a 75 ohm coaxial video cable, or special S/PDIF cable. See To record through the S/PDIF input.

Electric guitar direct-in

You can connect an electric guitar directly to your sound card using a 1/4 inch mono to 1/8 inch stereo adapter. The following diagram shows this setup:

Figure 29. Electric guitar direct in.

The 1/8 inch plug should be plugged into the sound card’s Line input, although plugging into the Mic input will also work. If you use the Line input, make sure you have selected Line-In on the Windows Record Control dialog box (Windows Mixer). If you use the Mic input, select Microphone. To open the Windows Mixer—double-click the Speaker icon that’s on your Windows taskbar to open the Play Control dialog box. In the Play Control dialog box, use the Options > Properties command, select Recording (under Adjust volume for), make sure Line-In and Microphone are checked, and click OK. In the Record Control dialog box, click the Select check box in either the Line-In or Microphone column, make sure the sliders are in the upper half of their range, and click OK. If you don’t see the Speaker icon on your taskbar, you can open the Windows Mixer by using the Control Panel > Hardware and Sound > Volume Control (Windows 7) command.

Electric guitar through effects rack

You can also plug an electric guitar into an effects rack, then send the output of the rack to the sound card’s input, as shown in the following diagram:

Figure 30. Electric guitar through effects rack.

This diagram assumes that the output of the rack is at line level (consult your rack’s documentation). If it is at pro level instead (+4 dB), and your sound card does not accept a +4 db input, you will need to attenuate (lower) the F/X rack’s signal. To do this, use a mixer between the rack’s output and the Y-adapter. If the rack has only a mono output, a 1/4 inch mono to 1/8 inch stereo adapter should be used instead of a Y-adapter.

If you want to connect a guitar amplifier’s direct output to the sound card, you should base your setup on this example.

Microphone direct-in

Microphones can be plugged into the sound card’s Mic input. Some inexpensive microphones are made especially for use with sound cards and come equipped with 1/8 inch plugs. However, better quality microphones take better quality cables, which do not terminate in 1/8 inch plugs. The following figure illustrates how to connect a microphone that terminates in a 1/4 inch plug to a 1/8 inch input:

Figure 31. Microphone direct in.

Home stereo, CD player, radio tuner, preamp output

The output of a stereo component can be connected to the sound card’s Line input, using a dual RCA to 1/8 inch stereo mini Y-adapter. Many portable cassette players come with this kind of adapter, or even with a single cable with all the necessary plugs. In the following diagram, a stereo component is connected to the Y-adapter using standard RCA cables:

Figure 32. Home stereo, CD player, radio tuner, preamp output.

Internal CD player

If you are using your computer’s internal CD player, and it does not have its audio output cable connected internally to the sound card, run a cable from the CD player’s Headphone jack to the card’s Line input. If there is no Headphone jack, you’ll need to use an external CD player.

Mixer

You can connect a mixer to the sound card with a setup of the following kind:

Figure 33. Mixer.

Let’s trace the signal flow in the above picture:

1.	Your pre-recorded tracks flow out of the sound card’s outputs into mixer inputs #1 and 2.

2.	Both the pre-recorded tracks and the live guitar’s sound flow into the main mixer outs, where you can hear them (monitor them) through the stereo amplifier and speakers.

3.

If you turn up the bus send #1 on the guitar input (mixer input #3), the guitar sound flows into a sound card line input out of bus #1. You could turn up the bus send #2 control on the guitar input if you wanted to use that instead, since both buses #1 and #2 are patched into the sound card’s line input. You could also use both bus sends at the same time to double the guitar’s mono signal if you wanted (not the usual way to record).

4.

Since you’re already hearing the guitar through the main outputs, you probably don’t want to hear its signal again coming back through the sound card’s outputs, so mute the sound card’s line-in on its Play Control page of its mixer software (not its Record Control page—you want to record the line-in, but not play it back).

5.	If you plug other instruments into other inputs, you can send them into your sound card’s line input by turning up bus send #1 and/or #2 on each of the mixer’s channels.

6.

If the guitar in the above picture had a stereo pickup and stereo cable, you could plug the left plug on the cable into input #3 and turn up bus send #1, and plug the right plug into input #4, and turn up bus send #2 on that input. You would then be sending a stereo signal from the guitar through buses #1 and #2 to the sound card’s line input.

7.	In the above setup, do not turn up the bus sends on inputs #1 or #2 (where the sound card’s line outputs connect to the mixer)—this creates a feedback loop, feeding the sound card’s outputs back into its inputs through the buses.

 

For more information, see:

Choosing inputs

Audio recording

Audio hardware (sound cards) and drivers

MIDI